Multiple section antenna



June 8, 1943. G. H. BROWN 2,321,454

MULTIPLE SECTION ANTENNA Yiled NOV. 22, 1941 A l Snventot wfyslraw/L Patented June 8, 1943 UNH STATES ATENT OFFICE MULTKPLE SECTION ANTENNA George H. Brown, Haddonfield, N. J., assigner t Radio Corporation of America a corporation of Delaware 10 Claims.

This invention relates to multiple section antennas and particularly to an improved antenna in which the outer conductors, consisting of a plurality of sections of concentric lines, are used as radiators and in which inner portions of the concentric lines are used as phasing reactors and a mechanical support.

The Franklin antenna is one in which several radiating sections are connected by non-radiating phasing sections. The radiating sections are conventional conductors and the phasing sections are folded conductors. In practice it is dilicult to develop folded sections which do not radiate and which oier the proper impedance to the applied currents. Since sectional antennas of the single conductor type are usually not selfsupporting, it becomes necessary to provide a support together with means for insulating the several sections.

One of the objects of the present invention is to provide an improved multiple section antenna. Another object is to provide an improved multiple section self-supporting antenna. Another object is to provide improved means whereby a multiple section antenna may be adjusted to produce a predetermined radiation pattern. An additional object is to provide means whereby a plurality of sections of concentric lines are connected so that applied currents establish radiation fields of predominantly the same phase from the several sections.

The invention will be described by referring to the accompanying drawing in which Fig. 1 is an elevational view of one embodiment of the invention; Fig. 2 is a graph representing the field pattern of the antenna of Fig. l; Fig. 3 is an elevational view of a vertical antenna arranged in accordance with the invention; and Fig. 4 is a sectional View along the line 4 4 of Fig. 1.

Referring to Fig. 1, on a grounded plate or screen I four sections of concentric transmission line are arranged as follows: The inner conductor 3 of the four sections is a continuous conductor on which are located four pairs of snorting plugs 5, 5', 'I, 'I, 9, 9' and II, II. Each pair of snorting plugs support one of the four sections of the outer conductors I3, I5, I'I, I9 of the transmission line. By way of example, the end conductors I3 and I9 are each 5/8 of the operating wave length long. The central conductors I5 and II are each of the operating wave length long. The adjacent edges of the outer conductors are separated by a small air gap. The centrally located outer conductors I5 and I'I are supported by metal elements 2l and 23. One of the supporting elements 23 may act as a portion of the concentric feed line 25 which is connected to the transmitter 2l or other radio device. The end conductors I3 and I9 are supported by metal elements 29, 3l which are located at voltage nodes.

The snorting plugs 5 and II are located near the ends of the end sections I3 and I9. The electrical location of these plugs is not important as they serve only as supports for the outer conductors I3 and I9. and 1, and 9' and II are so Vspaced with respect to each other that they, -in conjunction with the intervening concentric line conductors, constitute an inductive reactance so that the currents traversing the inside portion of the outer conductors I3, l5 and I'I, I9 and the inner conductor 3 between the plugs 5', 1' and 9', II', are phased as hereinafter described. The shorting plugs 1 and 9 at the central portion of the' antenna are spaced so that the antenna impedance matches the impedance of the concentric fed line 25.

The operation of the antenna is as follows: The currents applied to the central sections I5, I'I are distributed over the outside portions of the central sections as shown in the kgraph above the antenna of Fig. l. Since the central sections have a total length of 3A; of a wave at the operating frequency it follows that the current distribution will be a half wave 33 at the center of the antenna followed .by oppositely .polarized 1/8 waves 35, 3l at the remote ends of the central sections. The applied currents then flow along the inner walls of `the .outer conductors I5, I'I; along the snorting plugs 1', 9'; along the inner conductors to the snorting plugs 5 and II; along the plugs 5' and II'; and alongthe inner walls of the outer conductors 'I3 `and I 9. The current distribution on the end sections .I3 and I9 starts with 1/8 wave distribution of the same phase as the 1/8 wave distribution on the neighboring conductors I5 and II and then ends with half wave distribution Yas indicated by the curves 39, 4I, respectively. The distribution of currentsiiowing within the inner surfaces of the lconcentric lines, as distinguished from the outeror radiating surfaces, is not shownbecause these Ysurfaces do not radiate and therefore do not contribute to the response or radiation field estab-lished about the'antenna. V

The main radiation is establishedby the 4currents vof half wave distribution 33, 3.9, 4I. YThe outl of phase components corresponding to the 1/8 wave 35, 31, 43, 45 distribution, theoretically detract from the main radiation. This has not The adjacent snorting plugs 5' proven detrimental because in many cases the out of phase components tend to confine the eld to useful regions. For described lengths and spacings of snorting plugs, the field pattern shown in Fig. 2 was obtained. The main single lobe was resolved into two lobes by changing the spacing of the snorting plugs l and 9', Il. The eld pattern may be varied over a wide range by varying the lengths of the radiating portions and the reactance of the non-radiating portions.

The invention may be applied to an antenna for radiating vertically polarized Waves. Such an arrangement is shown in Fig. 3 in which the inner conductor 5I is the support for the an tenna. The inner conductor may be grounded and may be supplied with ground rods 53. Shorting plugs `55, 51, 5l', 58, 59', 6l, 6I and 63 are attached to the inner conductor. The snorting plugs serve two functions: the first is to support the outer conductors 65, El, 69 and 1I; the second is to provide non-radiating reactance sections of the type previously described by reference to lj'ig. l. The rst outer conductor section 65 is connected to the inner member of a concentric fed line 'I3 which is connected to the transmitter' l5, or receiver if the antenna is used for reception. The outer member of the fed line is connected to ground and to the inner conductor Y 5I of the antenna.

The spacing of the lowest plug 55 is adjusted to match the antenna impedance to the fed line impedance. The spacings of the adjacent pairs of snorting plugs 51-51, Bil-59', and BI-Bl are adjusted to obtain the desired reactance between tne adjacent radiating sections. The lowest section E5 is made of a wave length of the applied current. The central radiating sections 61, and 69 are each of a wave length. The highest section is made `L/ of a wave length. The current distribution of the several radiating sections is illustrated by a graph 'l1 which is a part of Fig. 3. The eld pattern of the antenna will be circular. In an antenna of this type the out of phase components do not necessarily indcate a loss because properly related to the in phase components, they tend to suppress sky wave radiation and to confine the main radiation to the useful path parallel to the earths surface.

While the invention has been described as composed of sections of concentric line it should be understood that the outer conductors need not be solid but may be fabricated from wires, or'screens. The vertical antenna may be provided with reflectors or directors, if a directive pattern is desired. Moreover, such reflectors or directors may be rotated or oscillated to produce a rotating or oscillating pattern.

.I claim las my invention: j

'1. A multisection antenna including an inner conductor, a plurality of separated outer conductors, and conductive means attached to said inner conductor for supporting said outer conductors and spaced to form reactive sections connecting said outer conductors in series.

2. A multisection antenna including an inner conductor, a plurality of separated and linearly arranged outer conductors, snorting plugs at` tached to said inner conductor and located in pairs connected respectively to adjacent outer conductors to form reactance sections therebetween effectively connecting said outer conductors in series, and means for effectively connecting a radio device to said antenna.

3. A multisection antenna including an inner conductor, a plurality of adjacent outer conductors, conductive means attached to said inner conductor for supporting said adjacent outer conductors and spaced to form reactive sections connecting said adjacent outer conductors in series, and means for connecting a radio device to said antenna.

4. A multisection antenna including an inner nonradiating conductor, a plurality of adjacent radiating outer conductors arranged in a line, snorting members attached to said inner and outer conductors and forming reactive sections connecting said adjacent radiating conductors in series so that the main radiation from said conductors is in the same phase, and means for connecting a radio device between the adjacent ends of two of said outer conductors.

5. A multisection antenna including an inner nonradiating conductor, a plurality of adjacent radiating outer conductors, snorting members attached to said inner and outer conductors and forming reactive sections connecting said adjacent radiating conductors in series so that the main radiation from said conductors is in the same phase, means for connecting a radio device between the adjacent ends of two of said outer conductors, and additional snorting members spaced with respect to said connecting means for adjusting the input impedance 'of said antenna.

6. A multisection antenna including an inner conductor, a plurality of adjacent outer conductors, conductive members attached to said inner conductor for supporting said adjacent outer conductors and spaced to form reactive sections connecting said adjacent outer conductors in series, and means for connecting a radio device between said inner conductor and one of said outer conductors.

7. A multisection antenna including an inner conductor, a plurality of adjacent outer conductors each of a length not less than a quarter of the operating wave length, conductive members attached to said inner conductor for supporting said adjacent outer conductors to form reactance sections connecting said adjacent outer conductors in series, and means for applying radio frequency currents to the adjacent ends of two of said outer conductors so that the current distribution corresponds to a plurality of half waves of the same phase.

8. A device according to claim 7 including means for adjusting the impedance between said adjacent ends. Y A

9. A multisection antenna including an inner conductor, a plurality of outer conductors arranged in'a line and each o f a length not less than a quarter of the operating wave length, conductive membersfattached to said inner conductor and to said outer conductors to form reactance sections connecting adjacent outer conductors in series, and connections vfor applying radio frequency currents to the adjacentlends of GEORGE HBROWN. 

